Underreamer.



J. W. BRAOKNEY.

UNDERREAMER. APPLIUATION PILED AUG. 10, 1908.

Patented Aug. 31, 1909,

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aangenaam e iti-lamentasite.; .1,11- fiel/euret .libertin-ite@ Q "elkeen-fetlieiCanet-ii ofgili e' 'env i ysetul Inipggovei iliei aine's, jewhichy the following is a` specification. 111 T hftiltt eilliir o ist, (ple, .com ),ajctffand tsign which will withstaiic Vthe extremelfsjpguglifutsageno which this class 'of tools is subjected.`

In the accompanyifngg, drawingsigforxning a part of this specification' Figiire l',-is a longitudinal section showing thennderreamer in its expanded state. Fig. Q',is an elevation showing the under-reamer in its contracted state. Fig.' 3,-is a detail longitudinal section showing the application of the` wedge for holding t-he cutters inY their contracted position. Fig. t5-is a detail perspective view of one'ot1 the cutters. Fig. 5,- is a cross-section taken on line 5--5 of Fig. l. of Fig. 1. i

In the drawings 10 designates a mandrel provided with the usual screw threaded connecting pin 11 on its upper end and with flattened portions or the engagement of tools therewith in the usual manner. The mandrel is provided with a central longitudinal bore 12 in which the cutter operating sprin is mounted. At its lowerend the mandre is Fig. (3,-is a section taken on line 6-G arms 13, one on each side, a space 14 being lett between the two arms for the reception of the upper ends of cutters 15. The end of the lnandrel is provided with two inwardly and upwardly inclined faces '16, these faces being symmetrically arranged in the niandrel and meeting at the center. Corresponding inclined faces 17 on the upper ends of cutters 15 bear against faces 16 and lie flatly against them when the cutters are in their expanded position as shown in Fig. 1. Each of the cutters is provided with encircling lugs or straps 18 which encircle a pin 19, the cutters being thus pivotally held together at approximately7 the middle part of their inner edges. Pin 19 is longer than the width yinthe vlower l offen.

et'got f invention to aperture"2231.191113 P111 '19V-rasees" tt the Qiodpassing.up/.a u n the mandrel,4 A? 'Hatte d portionQffispr ,viided on. rod Qltpassmg' etweenfafpaiifo pinsQG set i'n'the mandrel V by to k'eciirod 2t om tip idiadapted there ning out'v otits Icori-- 1101111111@ pins 25 `and, a coiled spring. 8`surrounding.v

dotted lines in Fig. 3, may be inserted to torce rod :2-1 downwardly and allow the cutters to contract.

The configuration of one of the cutters is .illustrated in Fig. 4, the other cutter being similar. It will be noted that the upper part of the cutters is narrower than the lower in the direction of pin 19, this narrow upper part working in space 11 between the two'downwardly depending arms 13. Then the cutters are in their expanded position their inner faces are brought solidly into contact with each other as indicated in Fig. 1, this solid contact and the pivotal connection of both cutters with pin 19 preventing the cutters from being expanded farther at their lower ends by any shock or strain. The slope of faces 16 and the strength of spring Q8 are relatively designed so as to prevent the lower ends of the cutters from being contracted by the-upward and inward pressure to which they are subjected during the operation of drilling.

The upper parts of thewidened lower or cutting ends of the cutters are provided with shoulders 31 arranged angularly with relation to each other and which bear upwardly and inwardly respectively against correspending shoulders 35 formed on the lower ends of downwardly depending arms 13. The parts are so proportioned that faces 33 are bearing firmly against each other at the saine time that faces 17 are bea-ring against i'aces 16 and shoulders 34 are pressing uprect' ppsitior'i I wijten the, cutters are renieyed',y 'i

Rendi A .collar 2 7 l.rests upon rod??? restsupontlie collant` ye illloper end the spring bearingl upwardly against an adend of bore 1:2v so that awedge 23, shown in -Thus an extremely the' stresses due to the .vv'ardly vand inwardly against shoulders formed which is stren rillingoperations.

From a comparison of Figs. 1 and 2 it will seenthat Jthe cutters move bodily up- I -Wardly 'alongsurfaces 16. This actiontakes A pla ce whenever the cutters emerge fronr the 1 the 'cutters are pressed-,downwardly and in- Wardly by the engagement of 'the lower end loftheeasing with shoulders 36 on' the cutters and they are thereby'fo'rcedjinto theposition show'n' ln'Fig. 2. As' soon asthe upper end of; the' mandrel 'theircontracted position Wedge 32 may be inserted .in-.slots 31 andcutter operating rod IQl'heldfinits lowerposition or the Wedge Amay be driven into the-mandrel to force' the lcperating rod24- downwardly after the un- 1 strong Construction is 'end of the rod, guideemerges from the top of the casing; and'while the cutters are still held in day of August, 1908.

der-realner has been. taken entirely from the A caslng. thenedagamst all of Having described my invention, what I claim as new and desire to secure by Letters Patent is:-

In an under-reanier, a hollow` mandrel, a spring-elevated rod mounted in the mandrel', a transverse pivot-pin secured to the lower rooves being rovided in the opposite' sides o lsaid mandrelp for said transverse pin, with apertures 21 and 22 opening therefrom respectively, aperture E21 being of' larger diameter and aperture 22 of smaller dia-meter than said transverse pin, and a plurality of cutters pivoted on the transverse pin.

In 'Witness that I cla-iin the foregoing I have hereunto 'subscribed n1y name this 3rd J. IV. BRACKN'EY. IVitnesses:

J Amis T. BARKELEW,

OLLTE PALMER. 

